A fuel cell is an energy conversion device that converts the chemical energy of a fuel directly into electrical energy. That is, the fuel cell uses a fuel gas and an oxidant, and employs a method of producing electric power by using the electrons generated during the redox reaction of the fuel gas and the oxidant. A membrane electrode assembly (MEA) of the fuel cell is a part in which an electrochemical reaction of hydrogen and oxygen occurs, and is composed of a cathode, an anode, and an electrolyte membrane, that is, an ion conductive electrolyte membrane.
A redox flow battery (oxidation-reduction flow battery) is a system in which an active material included in an electrolytic solution is oxidized and reduced and thus charged and discharged, and an electrochemical storage device that stores the chemical energy of the active material directly into electrical energy. A unit cell of the redox flow battery includes an electrode, an electrolyte, and an ion exchange membrane.
Fuel cells and redox flow batteries have been researched and developed as a next-generation energy source due to high energy efficiency and eco-friendly characteristics of less emission of contaminants. Ion exchange membrane materials for a fuel cell and a redox flow battery need to have characteristics of 1) prevention of the cross over of an electrolyte, 2) strong chemical resistance, 3) enhancement of mechanical properties, and 4) a low swelling ratio in addition to excellent proton conductivity. Accordingly, studies on the electrolyte membrane having the characteristics have been continued.